Meclizine, sold under the brand name Bonine, among others, is an antihistamine used to treat motion sickness and dizziness (vertigo).

Meclizine has been shown to have fewer dry mouth side effects than the traditional treatment for motion sickness, transdermal scopolamine.

Symptoms of a serious allergic reaction may include rash, itching, swelling, severe dizziness, and trouble breathing.

The drug depresses labyrinth excitability and vestibular stimulation, and it may affect the medullary chemoreceptor trigger zone.

[19] At the same time the drug was found to have only a small (and statistically insignificant) effect on the motion sensitivity of the utricles.

[19] Much as motion sickness arises from a discrepancy between multiple senses, meclizine most likely affects a wide array of sensory mechanisms related to self-motion while leaving the core vestibular response intact.

[20] Meclizine also has been reported to be a weak dopamine antagonist at D1-like and D2-like receptors[citation needed] but it does not cause catalepsy in mice, perhaps because of its anticholinergic activity.

[2] Despite its relatively short half-life, the drug is reported to remain effective for motion sickness for 12 - 24 hours.

[23] Meclizine has low bioavailability (22–32%) and a delayed onset to action in part due to its poor solubility in water (0.1 mg/ml) and gastrointestinal fluid.

[30] It is sold under the brand names Bonine, Bonamine, Antivert, Postafen, Sea Legs, and Dramamine II (Less Drowsy Formulation).